Air springs have been used for motor vehicles and various machines and other equipment for a number of years. Air springs provide cushioning between movable parts, primarily to absorb shock loads imparted thereon. The air spring usually consists of a flexible elastomeric reinforced sleeve that extends between a pair of end members. The sleeve is attached to the end members to form a pressured chamber therein. Depending on the specific air spring construction, there may be one or more pistons located within the flexible sleeve. The air spring is mounted on spaced components or parts of the vehicle or equipment.
The internal pressurized fluid, generally air, absorbs most of the shock impressed upon or experienced by one of the spaced end members by which the air spring is mounted. The end members move inwards and towards each other and also away and outwards from each other upon absorbing the imparted shock.
To prevent the end members from contacting each other during inward movement, many air springs have internal bumpers mounted on one of the end members. The bumper extends axially into the interior of the pressurized chamber. The bumper absorbs shock when the air spring experiences severe shocks and deflections and prevents a total collapse or deflection of the air spring in the event of an air spring failure.
Known internal bumpers include the solid elastomeric bumpers disclosed in U.S. Pat. Nos. 4,506,910 and 4,787,606. The bumpers are mounted on either end member of the air spring. The bumpers are attached to the end member by means of a post having an enlarged end over which the solid rubber bumper is mounted. When the bumper is made from solid rubber, hydraulic loading of the rubber occurs when the bumper is subjected to repetitive high forces, and this loading is transferred to the metal retainer.
U.S. Pat. No. 5,201,500 discloses a thermoplastic, non-solid bumper. The bumper is secured to a post by circumferentially arranged flexible fingers. While this bumper eliminates the issue of hydraulic loading of a solid rubber bumper, the disclosed bumper is subject to the fingers breaking off due to excessive or repetitive shock absorption The disclosed bumper is also more complex and costly to manufacture because of the flexible fingers.
The present invention is directed toward an improved bumper for an air spring that overcomes the limitations of the above mentioned prior art bumpers.